WASHINGTON (CNN) --Democrat Howard Dean has raised more than $7 million in the past three months for his White House bid, nearly half of which came from online contributions received in the past nine days, his campaign said.

The figure puts the former Vermont governor atop the Democratic field in fund-raising for the second quarter of the year, and firmly establishes him as a serious contender for the Democratic presidential nomination.

The campaigns, however, have not filed their campaign reports for the quarter yet, and Dean may not be the leader when it comes to the total cash on hand -- as opposed to what was raised this quarter.

Still, Dean's second-quarter success is noteworthy. Dean's campaign strategy has relied more on Internet word-of-mouth than any other major presidential campaign in history.

In the past nine days, the Dean campaign has raised more than $3.8 million, the bulk of which -- $3 million -- was contributed online.

In an e-mail sent Saturday night to campaign supporters, Dean announced raising over $6 million, calling the feat an "incredible milestone." He urged contributors to dig deeper into their pockets and raise an additional $500,000 by midnight Monday, the Federal Election Commission's deadline for second quarter contributions.

"We have already raced past all expectations. We now have the opportunity to truly shock the press and the pundits with our show of grass-roots strength," Dean said in his online pitch. "If we raise $6.5 million in the second quarter, we will have placed our candidacy irrefutably in the top tier, and we will transform the dynamic of this race."

The campaign quickly surpassed the $6.5 million threshold by Monday afternoon and reached its midnight fund-raising goal of $7 million by 10 p.m.

Although campaigns routinely underestimate their fund-raising to lower expectations and generate positive coverage if and when they exceed that amount, Dean's Democratic rivals concede that his lead for the quarter will likely hold when final detailed reports are filed with the Federal Election Commission on July 15.

"We're not going to beat Dean," said an aide for Sen. John Kerry, D-Massachusetts.

Fund-raising estimates provided by a number of Democratic sources previously had Dean raising $3.5 million to $4.5 million, below the three-month take of $5 million expected by both Kerry and Sen. John Edwards of North Carolina, who led the field in fund-raising at the end of March with $7.5 million.

Rep. Richard Gephardt of Missouri expects to have raised $4 million to $5 million this quarter, according to sources. Campaign sources close to Sen. Joe Lieberman of Connecticut said the 2000 vice presidential nominee is "aiming for $4 million."

Sen. Bob Graham of Florida, sources said, is expected to raise $2 million to $3 million; Rep. Dennis Kucinich, D-Ohio, more than $1 million; former Sen. Carol Moseley Braun of Illinois, $150,000; the Rev. Al Sharpton of New York, between $70,000 and $100,000.

Dean's fund-raising was at about $3.2 million slightly more than a week ago, the campaign said. He apparently benefited from news coverage of his official campaign kick-off event this past Monday, and his victory Friday in an online "primary" sponsored by the liberal advocacy group MoveOn.org, boosting his campaign coffers by an additional $2.8 million over eight days.

That gain came despite having to temporarily sideline his campaign to deal with his 17-year-old son's alleged involvement in a break-in at a Burlington, Vermont, country club, and after what was viewed by some as a shaky appearance on NBC's Meet the Press.

Important figures

Once the numbers are in, the campaigns are likely to debate which figures are more important: the amount raised or the amount of ready cash available to the campaign.

"The most important number out of the first six months is how much money you have in the bank, how much money do you have to compete with," said Kerry spokesman Robert Gibbs, before Dean's revised fund-raising estimates were announced. "We believe we're likely to be ahead of where we thought we would be only six months ago, and with enough money in the bank to win the nomination next year."

Kerry had more than $8 million in the bank at the start of April, the most of any Democratic candidate. He expects to have $11 million in available cash by Monday's midnight deadline, according to sources.

Dean had slightly more than $2 million in cash by the beginning of April, at least $300,000 of which has gone to a statewide television ad campaign in the first-in-the-nation caucus state of Iowa. Dean is the only presidential candidate currently airing television ads.

Despite Dean's better-than-expected showing this quarter, he and his rivals for the Democratic nomination are likely to be dwarfed financially by the sole Republican in the race.

President Bush is expected to bring in an additional $3 million for his re-election effort Monday from a pair of events in Florida, pushing the Bush-Cheney 2004 campaign's fund-raising total for the quarter to almost $30 million.